A British adventurer is among those aboard a submersible which has gone missing near the wreckage of the Titanic.

Hamish Harding, chairman of private plane firm Action Aviation, is understood to be aboard the five-person OceanGate Expeditions vessel which was reported overdue on Sunday evening about 435 miles south of St John’s, Newfoundland.

A major search and rescue operation being led by the US Coast Guard and involving military aircraft is under way.

On social media at the weekend, Mr Harding said he was “proud to finally announce” that he would be aboard the mission to the wreck of the Titanic – but added that due to the “worst winter in Newfoundland in 40 years, this mission is likely to be the first and only manned mission to the Titanic in 2023”.

Atlantic map
(Alamy/PA)

He continued: “A weather window has just opened up and we are going to attempt a dive tomorrow.

“We started steaming from St Johns, Newfoundland, Canada yesterday and are planning to start dive operations around 4am tomorrow morning. Until then we have a lot of preparations and briefings to do.”

OceanGate Expeditions said its focus was on those aboard the vessel and their families.

“We are deeply thankful for the extensive assistance we have received from several government agencies and deep sea companies in our efforts to re-establish contact with the submersible,” the company said in a statement.

“We are working toward the safe return of the crew members.”

Mr Harding is a holder of three Guinness World Records: longest duration at full ocean depth by a crewed vessel, longest distance traversed at full ocean depth by a crewed vessel and fastest circumnavigation via both Poles by aeroplane.

Two of these feats were achieved by Mr Harding and ocean explorer Victor Vescovo when they dived to the lowest depth of the Mariana Trench – the deepest part of the ocean – in a two-person deep-submergence vehicle in March 2021.

They spent four hours and 15 minutes traversing the deepest part of the ocean and travelled 2.88 miles at that depth.

Challenger Deep is about 186 miles south west of Guam in the western Pacific Ocean and has a depth in its Eastern Pool of 35,860ft.

In July 2019, Mr Harding was part of a team that achieved the fastest circumnavigation of Earth via both geographic poles by plane with a time of 46 hours, 40 minutes and 22 seconds.

In June last year, he travelled to space with fellow billionaire Jeff Bezos’s Blue Origin company.